/*
 * $Id: BlendComposite.java 4011 2011-05-05 16:19:34Z kschaefe $
 *
 * Dual-licensed under LGPL (Sun and Romain Guy) and BSD (Romain Guy).
 *
 * Copyright 2005 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * Copyright (c) 2006 Romain Guy <romain.guy@mac.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.jdesktop.swingx.graphics;

import java.awt.Composite;
import java.awt.CompositeContext;
import java.awt.RenderingHints;
import java.awt.image.ColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.DirectColorModel;
import java.awt.image.Raster;
import java.awt.image.RasterFormatException;
import java.awt.image.WritableRaster;

/**
 * <p>
 * A blend composite defines the rule according to which a drawing primitive
 * (known as the source) is mixed with existing graphics (know as the
 * destination.)
 * </p>
 * <p>
 * <code>BlendComposite</code> is an implementation of the
 * {@link java.awt.Composite} interface and must therefore be set as a state on
 * a {@link java.awt.Graphics2D} surface.
 * </p>
 * <p>
 * Please refer to {@link java.awt.Graphics2D#setComposite(java.awt.Composite)}
 * for more information on how to use this class with a graphics surface.
 * </p>
 * <h2>Blending Modes</h2>
 * <p>
 * This class offers a certain number of blending modes, or compositing rules.
 * These rules are inspired from graphics editing software packages, like
 * <em>Adobe Photoshop</em> or <em>The GIMP</em>.
 * </p>
 * <p>
 * Given the wide variety of implemented blending modes and the difficulty to
 * describe them with words, please refer to those tools to visually see the
 * result of these blending modes.
 * </p>
 * <h2>Opacity</h2>
 * <p>
 * Each blending mode has an associated opacity, defined as a float value
 * between 0.0 and 1.0. Changing the opacity controls the force with which the
 * compositing operation is applied. For instance, a composite with an opacity
 * of 0.0 will not draw the source onto the destination. With an opacity of 1.0,
 * the source will be fully drawn onto the destination, according to the
 * selected blending mode rule.
 * </p>
 * <p>
 * The opacity, or alpha value, is used by the composite instance to mutiply the
 * alpha value of each pixel of the source when being composited over the
 * destination.
 * </p>
 * <h2>Creating a Blend Composite</h2>
 * <p>
 * Blend composites can be created in various manners:
 * </p>
 * <ul>
 * <li>Use one of the pre-defined instance. Example:
 * <code>BlendComposite.Average</code>.</li>
 * <li>Derive one of the pre-defined instances by calling {@link #derive(float)}
 * or {@link #derive(BlendingMode)}. Deriving allows you to change either the
 * opacity or the blending mode. Example:
 * <code>BlendComposite.Average.derive(0.5f)</code>.</li>
 * <li>Use a factory method: {@link #getInstance(BlendingMode)} or
 * {@link #getInstance(BlendingMode, float)}.</li>
 * </ul>
 * <h2>Functionality Change in SwingX 1.6.3</h2>
 * <p>
 * Due to incorrect implementations of various blending modes incompatible
 * changes have occurred. The following will help users alleviate problems
 * during migration:
 * <ul>
 * <li>{@link BlendingMode#BLUE} and {@link BlendingMode#GREEN} have been
 * swapped.</li>
 * </ul>
 * <p>
 * 
 * @see org.jdesktop.swingx.graphics.BlendComposite.BlendingMode
 * @see java.awt.Graphics2D
 * @see java.awt.Composite
 * @see java.awt.AlphaComposite
 * @author Romain Guy <romain.guy@mac.com>
 * @author Karl Schaefer (support and additional modes)
 */
public final class BlendComposite implements Composite {
	/**
	 * A blending mode defines the compositing rule of a
	 * {@link org.jdesktop.swingx.graphics.BlendComposite}.
	 * 
	 * @author Romain Guy <romain.guy@mac.com>
	 * @author Karl Schaefer (support and additional modes)
	 */
	public enum BlendingMode {
		/**
		 * The {@code Average} blending mode produces an average of the source
		 * and blend colors. The image will push colors toward the middle,
		 * reducing the extremes.
		 */
		AVERAGE {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = (src[0] + dst[0]) >> 1;
				result[1] = (src[1] + dst[1]) >> 1;
				result[2] = (src[2] + dst[2]) >> 1;
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * Similar to {@link #AVERAGE}, but more severely lightens or darkens
		 * the edge colors.
		 */
		STAMP {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = Math.max(0, Math.min(255, dst[0] + 2 * src[0] - 256));
				result[1] = Math.max(0, Math.min(255, dst[1] + 2 * src[1] - 256));
				result[2] = Math.max(0, Math.min(255, dst[2] + 2 * src[2] - 256));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Darken} blend mode compares the color information for each
		 * pixel of the base and the blend color and applies the darker color as
		 * the result. Any pixels in the base image that are lighter than the
		 * blend color are replaced, and pixels that are darker are left
		 * unchanged. No part of the image will become lighter.
		 */
		DARKEN {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = Math.min(src[0], dst[0]);
				result[1] = Math.min(src[1], dst[1]);
				result[2] = Math.min(src[2], dst[2]);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Multiply} blend mode multiplies the base color with the
		 * blend color. The resulting color will always be darker, unless the
		 * blend color is white, which will result in no change. 100% opaque
		 * black multiplied with any color will result in black. As you overlay
		 * strokes of color with the Multiply blending mode, each stroke will
		 * result in darker and darker color.
		 */
		MULTIPLY {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = (src[0] * dst[0] + 2) >> 8;
				result[1] = (src[1] * dst[1] + 2) >> 8;
				result[2] = (src[2] * dst[2] + 2) >> 8;
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Color Burn} blending mode increases the contrast to darken
		 * the base color while reflecting the blend color. The darker the blend
		 * color, the more intensely the color will be applied in the base
		 * image. White as the blend color produces no change.
		 */
		COLOR_BURN {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] == 0 ? 0 : Math.max(0, 255 - (((255 - dst[0]) << 8) / src[0]));
				result[1] = src[1] == 0 ? 0 : Math.max(0, 255 - (((255 - dst[1]) << 8) / src[1]));
				result[2] = src[2] == 0 ? 0 : Math.max(0, 255 - (((255 - dst[2]) << 8) / src[2]));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * {@code Inverse Color Burn} is the same as {@link #COLOR_BURN Color
		 * Burn} with the source and destination swapped.
		 */
		INVERSE_COLOR_BURN {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0] == 0 ? 0 : Math.max(0, 255 - (((255 - src[0]) << 8) / dst[0]));
				result[1] = dst[1] == 0 ? 0 : Math.max(0, 255 - (((255 - src[1]) << 8) / dst[1]));
				result[2] = dst[2] == 0 ? 0 : Math.max(0, 255 - (((255 - src[2]) << 8) / dst[2]));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		SOFT_BURN {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0] + src[0] < 256 ? (dst[0] == 255 ? 255 : Math.min(255, (src[0] << 7) / (255 - dst[0])))
						: Math.max(0, 255 - (((255 - dst[0]) << 7) / src[0]));
				result[1] = dst[1] + src[1] < 256 ? (dst[1] == 255 ? 255 : Math.min(255, (src[1] << 7) / (255 - dst[1])))
						: Math.max(0, 255 - (((255 - dst[1]) << 7) / src[1]));
				result[2] = dst[2] + src[2] < 256 ? (dst[2] == 255 ? 255 : Math.min(255, (src[2] << 7) / (255 - dst[2])))
						: Math.max(0, 255 - (((255 - dst[2]) << 7) / src[2]));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Subtract} blend mode is similar to {@link #COLOR_BURN
		 * Color Burn} but instead of increasing contrast, it decreases
		 * brightness to darken the base color and reflect the blend color. It
		 * is also similar to the Multiply blend mode, but produces a much more
		 * intense result. White as the blend color produces no change.
		 * <p>
		 * This mode is also known as {@code Linear Burn}.
		 */
		SUBTRACT {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = Math.max(0, src[0] + dst[0] - 256);
				result[1] = Math.max(0, src[1] + dst[1] - 256);
				result[2] = Math.max(0, src[2] + dst[2] - 256);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Lighten} blending mode compares the color information for
		 * each pixel of the base and the blend color and applies the lighter
		 * color as the result. Any pixels in the base image that are darker
		 * than the blend color are replaced, and pixels that are lighter are
		 * left unchanged. No part of the image will become darker.
		 */
		LIGHTEN {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = Math.max(src[0], dst[0]);
				result[1] = Math.max(src[1], dst[1]);
				result[2] = Math.max(src[2], dst[2]);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Screen} blending mode is the opposite of the
		 * {@link #MULTIPLY Multiply} mode in that it multiples the inverse of
		 * the base color with the blend color. What this means is that your
		 * image will get lighter overall. In areas where the blend color is
		 * black, the base image will be unchanged, and in areas where the blend
		 * or base color is white, the result will be no change. Dark areas in
		 * the base image will become significantly lighter, and bright areas
		 * will become only slightly lighter.
		 */
		SCREEN {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = 255 - ((255 - src[0]) * (255 - dst[0]) >> 8);
				result[1] = 255 - ((255 - src[1]) * (255 - dst[1]) >> 8);
				result[2] = 255 - ((255 - src[2]) * (255 - dst[2]) >> 8);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Color Dodge} blending mode is essentially the opposite of
		 * {@link #COLOR_BURN Color Burn}. The {@code Color Dodge} blending mode
		 * decreases the contrast to brighten the base color while reflecting
		 * the blend color. The lighter the blend color, the more significant
		 * the color dodge effect will be making the result brighter, with less
		 * contrast, and tinted toward the blend color. Black as the blend color
		 * produces no change.
		 */
		COLOR_DODGE {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] == 255 ? 255 : Math.min((dst[0] << 8) / (255 - src[0]), 255);
				result[1] = src[1] == 255 ? 255 : Math.min((dst[1] << 8) / (255 - src[1]), 255);
				result[2] = src[2] == 255 ? 255 : Math.min((dst[2] << 8) / (255 - src[2]), 255);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * {@code Inverse Color Dodge} is the same as {@link #COLOR_DODGE Color
		 * Dodge} with the source and destination swapped.
		 */
		INVERSE_COLOR_DODGE {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0] == 255 ? 255 : Math.min((src[0] << 8) / (255 - dst[0]), 255);
				result[1] = dst[1] == 255 ? 255 : Math.min((src[1] << 8) / (255 - dst[1]), 255);
				result[2] = dst[2] == 255 ? 255 : Math.min((src[2] << 8) / (255 - dst[2]), 255);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		SOFT_DODGE {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0] + src[0] < 256 ? (src[0] == 255 ? 255 : Math.min(255, (dst[0] << 7) / (255 - src[0])))
						: Math.max(0, 255 - (((255 - src[0]) << 7) / dst[0]));
				result[1] = dst[1] + src[1] < 256 ? (src[1] == 255 ? 255 : Math.min(255, (dst[1] << 7) / (255 - src[1])))
						: Math.max(0, 255 - (((255 - src[1]) << 7) / dst[1]));
				result[2] = dst[2] + src[2] < 256 ? (src[2] == 255 ? 255 : Math.min(255, (dst[2] << 7) / (255 - src[2])))
						: Math.max(0, 255 - (((255 - src[2]) << 7) / dst[2]));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * {@code Add} is the opposite of {@link #SUBTRACT Subtract}. It
		 * increases brightness to lighten the base color and reflect the blend
		 * color. It is also similar to the {@link #SCREEN Screen} blend mode,
		 * but produces a more intense result. Black as the blend color produces
		 * no change.
		 * <p>
		 * This mode is also known as {@code Linear Dodge}.
		 */
		ADD {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = Math.min(255, src[0] + dst[0]);
				result[1] = Math.min(255, src[1] + dst[1]);
				result[2] = Math.min(255, src[2] + dst[2]);
				result[3] = Math.min(255, src[3] + dst[3]);
			}
		},

		/**
		 * The {@code Overlay} blending mode preserves the highlights and
		 * shadows of the base color while mixing the base color and the blend
		 * color. It is a combination of the {@link #MULTIPLY Multiply} and
		 * {@link #SCREEN Screen} blending modes--multiplying the dark areas,
		 * and screening the light areas. A blend color of 50% gray has no
		 * effect on the base image.
		 */
		OVERLAY {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0] < 128 ? dst[0] * src[0] >> 7 : 255 - ((255 - dst[0]) * (255 - src[0]) >> 7);
				result[1] = dst[1] < 128 ? dst[1] * src[1] >> 7 : 255 - ((255 - dst[1]) * (255 - src[1]) >> 7);
				result[2] = dst[2] < 128 ? dst[2] * src[2] >> 7 : 255 - ((255 - dst[2]) * (255 - src[2]) >> 7);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Soft Light} blend mode creates a subtle lighter or darker
		 * result depending on the brightness of the blend color. Blend colors
		 * that are more than 50% brightness will lighten the base image and
		 * colors that are less than 50% brightness will darken the base image.
		 * Pure black will create a slightly darker result; pure white will
		 * create a slightly lighter result, and 50% gray will have no effect on
		 * the base image.
		 */
		SOFT_LIGHT {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				int mRed = src[0] * dst[0] / 255;
				int mGreen = src[1] * dst[1] / 255;
				int mBlue = src[2] * dst[2] / 255;
				result[0] = mRed + dst[0] * (255 - ((255 - dst[0]) * (255 - src[0]) / 255) - mRed) / 255;
				result[1] = mGreen + dst[1] * (255 - ((255 - dst[1]) * (255 - src[1]) / 255) - mGreen) / 255;
				result[2] = mBlue + dst[2] * (255 - ((255 - dst[2]) * (255 - src[2]) / 255) - mBlue) / 255;
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * {@code Hard Light} drastically lightens or darkens the base image
		 * depending on the brightness of the blend color. The effect is more
		 * intense than {@link #SOFT_LIGHT Soft Light} because the contrast is
		 * also increased. Blend colors that are more than 50% brightness will
		 * lighten the base image in the same way as the screen blending mode.
		 * Colors that are less than 50% brightness will darken the base image
		 * in the same way as the multiply blending mode. Pure black will result
		 * in black; pure white will create a white result, and 50% gray will
		 * have no effect on the base image.
		 */
		HARD_LIGHT {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] < 128 ? dst[0] * src[0] >> 7 : 255 - ((255 - src[0]) * (255 - dst[0]) >> 7);
				result[1] = src[1] < 128 ? dst[1] * src[1] >> 7 : 255 - ((255 - src[1]) * (255 - dst[1]) >> 7);
				result[2] = src[2] < 128 ? dst[2] * src[2] >> 7 : 255 - ((255 - src[2]) * (255 - dst[2]) >> 7);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * Burns or dodges the colors by increasing or decreasing the contrast,
		 * depending on the blend color. If the blend color is lighter than 50%
		 * grey, the image is lightened by decreasing the contrast. If the blend
		 * color is darker than 50% grey, the image is darkened by increasing
		 * the contrast.
		 */
		VIVID_LIGHT {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] < 128 ? src[0] == 0 ? 0 : Math.max(0, 255 - ((255 - dst[0]) << 7) / src[0])
						: src[0] == 255 ? 255 : Math.min(255, (dst[0] << 7) / (255 - src[0]));
				result[1] = src[1] < 128 ? src[1] == 0 ? 0 : Math.max(0, 255 - ((255 - dst[1]) << 7) / src[1])
						: src[1] == 255 ? 255 : Math.min(255, (dst[1] << 7) / (255 - src[1]));
				result[2] = src[2] < 128 ? src[2] == 0 ? 0 : Math.max(0, 255 - ((255 - dst[2]) << 7) / src[2])
						: src[2] == 255 ? 255 : Math.min(255, (dst[2] << 7) / (255 - src[2]));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		LINEAR_LIGHT {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] < 128 ? Math.max(0, dst[0] + (src[0] << 1) - 255) : Math.min(255, dst[0]
						+ (src[0] - 128 << 1));
				result[1] = src[1] < 128 ? Math.max(0, dst[1] + (src[1] << 1) - 255) : Math.min(255, dst[1]
						+ (src[1] - 128 << 1));
				result[2] = src[2] < 128 ? Math.max(0, dst[2] + (src[2] << 1) - 255) : Math.min(255, dst[2]
						+ (src[2] - 128 << 1));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		PIN_LIGHT {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] < 128 ? Math.min(dst[0], src[0] << 1) : Math.max(dst[0], (src[0] - 128) << 1);
				result[1] = src[1] < 128 ? Math.min(dst[1], src[1] << 1) : Math.max(dst[1], (src[1] - 128) << 1);
				result[2] = src[2] < 128 ? Math.min(dst[2], src[2] << 1) : Math.max(dst[2], (src[2] - 128) << 1);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		HARD_MIX {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] < 256 - dst[0] ? 0 : 255;
				result[1] = src[1] < 256 - dst[1] ? 0 : 255;
				result[2] = src[2] < 256 - dst[2] ? 0 : 255;
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		REFLECT {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] == 255 ? 255 : Math.min(255, dst[0] * dst[0] / (255 - src[0]));
				result[1] = src[1] == 255 ? 255 : Math.min(255, dst[1] * dst[1] / (255 - src[1]));
				result[2] = src[2] == 255 ? 255 : Math.min(255, dst[2] * dst[2] / (255 - src[2]));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		GLOW {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0] == 255 ? 255 : Math.min(255, src[0] * src[0] / (255 - dst[0]));
				result[1] = dst[1] == 255 ? 255 : Math.min(255, src[1] * src[1] / (255 - dst[1]));
				result[2] = dst[2] == 255 ? 255 : Math.min(255, src[2] * src[2] / (255 - dst[2]));
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		FREEZE {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0] == 0 ? 0 : Math.max(0, 255 - (255 - dst[0]) * (255 - dst[0]) / src[0]);
				result[1] = src[1] == 0 ? 0 : Math.max(0, 255 - (255 - dst[1]) * (255 - dst[1]) / src[1]);
				result[2] = src[2] == 0 ? 0 : Math.max(0, 255 - (255 - dst[2]) * (255 - dst[2]) / src[2]);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		HEAT {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0] == 0 ? 0 : Math.max(0, 255 - (255 - src[0]) * (255 - src[0]) / dst[0]);
				result[1] = dst[1] == 0 ? 0 : Math.max(0, 255 - (255 - src[1]) * (255 - src[1]) / dst[1]);
				result[2] = dst[2] == 0 ? 0 : Math.max(0, 255 - (255 - src[2]) * (255 - src[2]) / dst[2]);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Difference} blending mode highlights the differences
		 * between the blend layer and the base layer. The more technical
		 * explanation is that the blend color is subtracted from the base
		 * color--or vice-versa, depending on the brightness--and the result is
		 * the difference between them. When white is the blend color, the base
		 * image is inverted. When black is the blend color, there is no change.
		 */
		DIFFERENCE {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = Math.abs(dst[0] - src[0]);
				result[1] = Math.abs(dst[1] - src[1]);
				result[2] = Math.abs(dst[2] - src[2]);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Exclusion} blending mode works very much like
		 * {@link #DIFFERENCE Difference} but the contrast is lower. When white
		 * is the blend color, the base image is inverted. When black is the
		 * blend color, there is no change.
		 */
		EXCLUSION {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0] + src[0] - (dst[0] * src[0] >> 7);
				result[1] = dst[1] + src[1] - (dst[1] * src[1] >> 7);
				result[2] = dst[2] + src[2] - (dst[2] * src[2] >> 7);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Hue} blend mode applies the hue of the blend color to the
		 * base image while retaining the luminance and saturation of the base
		 * image. It gives the base image a tinted effect where the tinting is
		 * darkest in areas of high saturation. Where the blend color is a shade
		 * of gray (0% saturation), the base image is desaturated and where the
		 * base image is gray, the Hue blending mode has no effect.
		 */
		HUE {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				float[] srcHSL = new float[3];
				ColorUtilities.RGBtoHSL(src[0], src[1], src[2], srcHSL);
				float[] dstHSL = new float[3];
				ColorUtilities.RGBtoHSL(dst[0], dst[1], dst[2], dstHSL);

				ColorUtilities.HSLtoRGB(srcHSL[0], dstHSL[1], dstHSL[2], result);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Saturation} blending mode applies the saturation of the
		 * blend color to the base image while retaining the hue and luminance
		 * of the base image. Neutral tones (black, white, and gray) in the
		 * blend will desaturate the base image. Neutral areas in the base image
		 * will not be changed by the saturation blending mode.
		 */
		SATURATION {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				float[] srcHSL = new float[3];
				ColorUtilities.RGBtoHSL(src[0], src[1], src[2], srcHSL);
				float[] dstHSL = new float[3];
				ColorUtilities.RGBtoHSL(dst[0], dst[1], dst[2], dstHSL);

				ColorUtilities.HSLtoRGB(dstHSL[0], srcHSL[1], dstHSL[2], result);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Color} blending mode applies the hue and saturation of the
		 * blend color to the base image while retaining the luminance of the
		 * base image. Simply put, it colors the base image. Neutral blend
		 * colors will desaturate the base image.
		 */
		COLOR {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				float[] srcHSL = new float[3];
				ColorUtilities.RGBtoHSL(src[0], src[1], src[2], srcHSL);
				float[] dstHSL = new float[3];
				ColorUtilities.RGBtoHSL(dst[0], dst[1], dst[2], dstHSL);

				ColorUtilities.HSLtoRGB(srcHSL[0], srcHSL[1], dstHSL[2], result);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * The {@code Luminosity} blending mode applies the luminosity
		 * (brightness) of the blend colors to the base image while retaining
		 * the hue and saturation of the base image. {@code Luminosity} is the
		 * opposite of the {@link #COLOR Color} blending mode.
		 */
		LUMINOSITY {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				float[] srcHSL = new float[3];
				ColorUtilities.RGBtoHSL(src[0], src[1], src[2], srcHSL);
				float[] dstHSL = new float[3];
				ColorUtilities.RGBtoHSL(dst[0], dst[1], dst[2], dstHSL);

				ColorUtilities.HSLtoRGB(dstHSL[0], dstHSL[1], srcHSL[2], result);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * This one is the "opposite" of difference mode. Note that it is NOT
		 * difference mode inverted, because black and white return the same
		 * result, but colors between become brighter instead of darker. This
		 * mode can be used to invert parts of the base image, but NOT to
		 * compare two images.
		 */
		NEGATION {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = 255 - Math.abs(255 - dst[0] - src[0]);
				result[1] = 255 - Math.abs(255 - dst[1] - src[1]);
				result[2] = 255 - Math.abs(255 - dst[2] - src[2]);
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * Keeps the red channel from the blend image and the green and blue
		 * channels from the base image.
		 */
		RED {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = src[0];
				result[1] = dst[1];
				result[2] = dst[2];
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * Keeps the green channel from the blend image and the red and blue
		 * channels from the base image.
		 */
		GREEN {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0];
				result[1] = src[1];
				result[2] = dst[2];
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},

		/**
		 * Keeps the blue channel from the blend image and the red and green
		 * channels from the base image.
		 */
		BLUE {
			@Override
			void blend(int[] src, int[] dst, int[] result) {
				result[0] = dst[0];
				result[1] = dst[1];
				result[2] = src[2];
				result[3] = Math.min(255, src[3] + dst[3] - (src[3] * dst[3]) / 255);
			}
		},
		;

		/**
		 * Blends the input colors into the result.
		 * 
		 * @param src
		 *            the source RGBA
		 * @param dst
		 *            the destination RGBA
		 * @param result
		 *            the result RGBA
		 * @throws NullPointerException
		 *             if any argument is {@code null}
		 */
		abstract void blend(int[] src, int[] dst, int[] result);
	}

	public static final BlendComposite Average = new BlendComposite(BlendingMode.AVERAGE);
	public static final BlendComposite Multiply = new BlendComposite(BlendingMode.MULTIPLY);
	public static final BlendComposite Screen = new BlendComposite(BlendingMode.SCREEN);
	public static final BlendComposite Darken = new BlendComposite(BlendingMode.DARKEN);
	public static final BlendComposite Lighten = new BlendComposite(BlendingMode.LIGHTEN);
	public static final BlendComposite Overlay = new BlendComposite(BlendingMode.OVERLAY);
	public static final BlendComposite HardLight = new BlendComposite(BlendingMode.HARD_LIGHT);
	public static final BlendComposite SoftLight = new BlendComposite(BlendingMode.SOFT_LIGHT);
	public static final BlendComposite VividLight = new BlendComposite(BlendingMode.VIVID_LIGHT);
	public static final BlendComposite LinearLight = new BlendComposite(BlendingMode.LINEAR_LIGHT);
	public static final BlendComposite PinLight = new BlendComposite(BlendingMode.PIN_LIGHT);
	public static final BlendComposite HardMix = new BlendComposite(BlendingMode.HARD_MIX);
	public static final BlendComposite Difference = new BlendComposite(BlendingMode.DIFFERENCE);
	public static final BlendComposite Negation = new BlendComposite(BlendingMode.NEGATION);
	public static final BlendComposite Exclusion = new BlendComposite(BlendingMode.EXCLUSION);
	public static final BlendComposite ColorDodge = new BlendComposite(BlendingMode.COLOR_DODGE);
	public static final BlendComposite InverseColorDodge = new BlendComposite(BlendingMode.INVERSE_COLOR_DODGE);
	public static final BlendComposite SoftDodge = new BlendComposite(BlendingMode.SOFT_DODGE);
	public static final BlendComposite ColorBurn = new BlendComposite(BlendingMode.COLOR_BURN);
	public static final BlendComposite InverseColorBurn = new BlendComposite(BlendingMode.INVERSE_COLOR_BURN);
	public static final BlendComposite SoftBurn = new BlendComposite(BlendingMode.SOFT_BURN);
	public static final BlendComposite Reflect = new BlendComposite(BlendingMode.REFLECT);
	public static final BlendComposite Glow = new BlendComposite(BlendingMode.GLOW);
	public static final BlendComposite Freeze = new BlendComposite(BlendingMode.FREEZE);
	public static final BlendComposite Heat = new BlendComposite(BlendingMode.HEAT);
	public static final BlendComposite Add = new BlendComposite(BlendingMode.ADD);
	public static final BlendComposite Subtract = new BlendComposite(BlendingMode.SUBTRACT);
	public static final BlendComposite Stamp = new BlendComposite(BlendingMode.STAMP);
	public static final BlendComposite Red = new BlendComposite(BlendingMode.RED);
	public static final BlendComposite Green = new BlendComposite(BlendingMode.GREEN);
	public static final BlendComposite Blue = new BlendComposite(BlendingMode.BLUE);
	public static final BlendComposite Hue = new BlendComposite(BlendingMode.HUE);
	public static final BlendComposite Saturation = new BlendComposite(BlendingMode.SATURATION);
	public static final BlendComposite Color = new BlendComposite(BlendingMode.COLOR);
	public static final BlendComposite Luminosity = new BlendComposite(BlendingMode.LUMINOSITY);

	private final float alpha;
	private final BlendingMode mode;

	private BlendComposite(BlendingMode mode) {
		this(mode, 1.0f);
	}

	private BlendComposite(BlendingMode mode, float alpha) {
		this.mode = mode;

		if (alpha < 0.0f || alpha > 1.0f) {
			throw new IllegalArgumentException("alpha must be comprised between 0.0f and 1.0f");
		}
		this.alpha = alpha;
	}

	/**
	 * <p>
	 * Creates a new composite based on the blending mode passed as a parameter.
	 * A default opacity of 1.0 is applied.
	 * </p>
	 *
	 * @param mode
	 *            the blending mode defining the compositing rule
	 * @return a new <code>BlendComposite</code> based on the selected blending
	 *         mode, with an opacity of 1.0
	 */
	public static BlendComposite getInstance(BlendingMode mode) {
		return new BlendComposite(mode);
	}

	/**
	 * <p>
	 * Creates a new composite based on the blending mode and opacity passed as
	 * parameters. The opacity must be a value between 0.0 and 1.0.
	 * </p>
	 *
	 * @param mode
	 *            the blending mode defining the compositing rule
	 * @param alpha
	 *            the constant alpha to be multiplied with the alpha of the
	 *            source. <code>alpha</code> must be a floating point between
	 *            0.0 and 1.0.
	 * @throws IllegalArgumentException
	 *             if the opacity is less than 0.0 or greater than 1.0
	 * @return a new <code>BlendComposite</code> based on the selected blending
	 *         mode and opacity
	 */
	public static BlendComposite getInstance(BlendingMode mode, float alpha) {
		return new BlendComposite(mode, alpha);
	}

	/**
	 * <p>
	 * Returns a <code>BlendComposite</code> object that uses the specified
	 * blending mode and this object's alpha value. If the newly specified
	 * blending mode is the same as this object's, this object is returned.
	 * </p>
	 *
	 * @param mode
	 *            the blending mode defining the compositing rule
	 * @return a <code>BlendComposite</code> object derived from this object,
	 *         that uses the specified blending mode
	 */
	public BlendComposite derive(BlendingMode mode) {
		return this.mode == mode ? this : new BlendComposite(mode, getAlpha());
	}

	/**
	 * <p>
	 * Returns a <code>BlendComposite</code> object that uses the specified
	 * opacity, or alpha, and this object's blending mode. If the newly
	 * specified opacity is the same as this object's, this object is returned.
	 * </p>
	 *
	 * @param alpha
	 *            the constant alpha to be multiplied with the alpha of the
	 *            source. <code>alpha</code> must be a floating point between
	 *            0.0 and 1.0.
	 * @throws IllegalArgumentException
	 *             if the opacity is less than 0.0 or greater than 1.0
	 * @return a <code>BlendComposite</code> object derived from this object,
	 *         that uses the specified blending mode
	 */
	public BlendComposite derive(float alpha) {
		return this.alpha == alpha ? this : new BlendComposite(getMode(), alpha);
	}

	/**
	 * <p>
	 * Returns the opacity of this composite. If no opacity has been defined,
	 * 1.0 is returned.
	 * </p>
	 *
	 * @return the alpha value, or opacity, of this object
	 */
	public float getAlpha() {
		return alpha;
	}

	/**
	 * <p>
	 * Returns the blending mode of this composite.
	 * </p>
	 *
	 * @return the blending mode used by this object
	 */
	public BlendingMode getMode() {
		return mode;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public int hashCode() {
		return Float.floatToIntBits(alpha) * 31 + mode.ordinal();
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public boolean equals(Object obj) {
		if (!(obj instanceof BlendComposite)) {
			return false;
		}

		BlendComposite bc = (BlendComposite) obj;
		return mode == bc.mode && alpha == bc.alpha;
	}

	private static boolean isRgbColorModel(ColorModel cm) {
		if (cm instanceof DirectColorModel && cm.getTransferType() == DataBuffer.TYPE_INT) {
			DirectColorModel directCM = (DirectColorModel) cm;

			return directCM.getRedMask() == 0x00FF0000 && directCM.getGreenMask() == 0x0000FF00
					&& directCM.getBlueMask() == 0x000000FF
					&& (directCM.getNumComponents() == 3 || directCM.getAlphaMask() == 0xFF000000);
		}

		return false;
	}

	private static boolean isBgrColorModel(ColorModel cm) {
		if (cm instanceof DirectColorModel && cm.getTransferType() == DataBuffer.TYPE_INT) {
			DirectColorModel directCM = (DirectColorModel) cm;

			return directCM.getRedMask() == 0x000000FF && directCM.getGreenMask() == 0x0000FF00
					&& directCM.getBlueMask() == 0x00FF0000
					&& (directCM.getNumComponents() == 3 || directCM.getAlphaMask() == 0xFF000000);
		}

		return false;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public CompositeContext createContext(ColorModel srcColorModel, ColorModel dstColorModel, RenderingHints hints) {
		if (isRgbColorModel(srcColorModel) && isRgbColorModel(dstColorModel)) {
			return new BlendingRgbContext(this);
		} else if (isBgrColorModel(srcColorModel) && isBgrColorModel(dstColorModel)) {
			return new BlendingBgrContext(this);
		}

		throw new RasterFormatException("Incompatible color models:\n  " + srcColorModel + "\n  " + dstColorModel);
	}

	private static abstract class BlendingContext implements CompositeContext {
		protected final BlendComposite composite;

		private BlendingContext(BlendComposite composite) {
			this.composite = composite;
		}

		@Override
		public void dispose() {
		}
	}

	private static class BlendingRgbContext extends BlendingContext {
		private BlendingRgbContext(BlendComposite composite) {
			super(composite);
		}

		@Override
		public void compose(Raster src, Raster dstIn, WritableRaster dstOut) {
			int width = Math.min(src.getWidth(), dstIn.getWidth());
			int height = Math.min(src.getHeight(), dstIn.getHeight());

			float alpha = composite.getAlpha();

			int[] result = new int[4];
			int[] srcPixel = new int[4];
			int[] dstPixel = new int[4];
			int[] srcPixels = new int[width];
			int[] dstPixels = new int[width];

			for (int y = 0; y < height; y++) {
				src.getDataElements(0, y, width, 1, srcPixels);
				dstIn.getDataElements(0, y, width, 1, dstPixels);
				for (int x = 0; x < width; x++) {
					// pixels are stored as INT_ARGB
					// our arrays are [R, G, B, A]
					int pixel = srcPixels[x];
					srcPixel[0] = (pixel >> 16) & 0xFF;
					srcPixel[1] = (pixel >> 8) & 0xFF;
					srcPixel[2] = (pixel) & 0xFF;
					srcPixel[3] = (pixel >> 24) & 0xFF;

					pixel = dstPixels[x];
					dstPixel[0] = (pixel >> 16) & 0xFF;
					dstPixel[1] = (pixel >> 8) & 0xFF;
					dstPixel[2] = (pixel) & 0xFF;
					dstPixel[3] = (pixel >> 24) & 0xFF;

					composite.getMode().blend(srcPixel, dstPixel, result);

					// mixes the result with the opacity
					dstPixels[x] = ((int) (dstPixel[3] + (result[3] - dstPixel[3]) * alpha) & 0xFF) << 24
							| ((int) (dstPixel[0] + (result[0] - dstPixel[0]) * alpha) & 0xFF) << 16
							| ((int) (dstPixel[1] + (result[1] - dstPixel[1]) * alpha) & 0xFF) << 8
							| (int) (dstPixel[2] + (result[2] - dstPixel[2]) * alpha) & 0xFF;
				}
				dstOut.setDataElements(0, y, width, 1, dstPixels);
			}
		}
	}

	private static class BlendingBgrContext extends BlendingContext {
		private BlendingBgrContext(BlendComposite composite) {
			super(composite);
		}

		@Override
		public void compose(Raster src, Raster dstIn, WritableRaster dstOut) {
			int width = Math.min(src.getWidth(), dstIn.getWidth());
			int height = Math.min(src.getHeight(), dstIn.getHeight());

			float alpha = composite.getAlpha();

			int[] result = new int[4];
			int[] srcPixel = new int[4];
			int[] dstPixel = new int[4];
			int[] srcPixels = new int[width];
			int[] dstPixels = new int[width];

			for (int y = 0; y < height; y++) {
				src.getDataElements(0, y, width, 1, srcPixels);
				dstIn.getDataElements(0, y, width, 1, dstPixels);
				for (int x = 0; x < width; x++) {
					// pixels are stored as INT_ABGR
					// our arrays are [R, G, B, A]
					int pixel = srcPixels[x];
					srcPixel[0] = (pixel) & 0xFF;
					srcPixel[1] = (pixel >> 8) & 0xFF;
					srcPixel[2] = (pixel >> 16) & 0xFF;
					srcPixel[3] = (pixel >> 24) & 0xFF;

					pixel = dstPixels[x];
					dstPixel[0] = (pixel) & 0xFF;
					dstPixel[1] = (pixel >> 8) & 0xFF;
					dstPixel[2] = (pixel >> 16) & 0xFF;
					dstPixel[3] = (pixel >> 24) & 0xFF;

					composite.getMode().blend(srcPixel, dstPixel, result);

					// mixes the result with the opacity
					dstPixels[x] = ((int) (dstPixel[3] + (result[3] - dstPixel[3]) * alpha) & 0xFF) << 24
							| ((int) (dstPixel[0] + (result[0] - dstPixel[0]) * alpha) & 0xFF)
							| ((int) (dstPixel[1] + (result[1] - dstPixel[1]) * alpha) & 0xFF) << 8
							| ((int) (dstPixel[2] + (result[2] - dstPixel[2]) * alpha) & 0xFF) << 16;
				}
				dstOut.setDataElements(0, y, width, 1, dstPixels);
			}
		}
	}
}
